England will attempt to defy expectations and deliver a performance against South Africa today which may prove to be the defining match of a long winter campaign.

Victory at the Kensington Oval would almost certainly ensure England's qualification for the World Cup semi-finals for the first time since 1992 and ease the pressure on several key members of the tour party.

It would mark a significant achievement for a side who have rarely threatened to develop into major challengers and only have wins over Canada, Kenya, Ireland and Bangladesh to show for their six weeks in the Caribbean.

But it could also represent a new lease of life following a winter where England have suffered an Ashes whitewash and only rescued a miserable one-day series with a remarkable series of results to somehow snatch the Commonwealth Bank series.

Coach Duncan Fletcher has been urged to end his seven-year reign for most of the winter and captain Michael Vaughan's struggles with the bat during this tournament have added to the pressure on the England management.

If, however, they could somehow click into gear as they did in Australia and beat South Africa, who were rated the number one one-day team in the world until last week's shock defeat by Bangladesh, the pressure would be off and England could look forward to a semi-final for the first time in 15 years. "It would be nice to win it for the coach, the players, all the supporters and it would be great to progress in this World Cup," said captain Vaughan, who has scored only 42 runs in his last five innings in the tournament.

"Duncan's been under a lot of criticism and I believe he's a fantastic coach and it would be great if we could progress in the tournament as much for him as anyone."

Vaughan believes the scepticism among the English supporters and media alike can only spur his side on to produce the kind of unexpected display which enabled them to bounce back from their lowest ebb to lift the Commonwealth Bank series trophy.

"We know we've been written off before and we know we've had periods when we haven't played great cricket and then in the last four games in Australia we were outstanding," said Vaughan. "Potentially there are four games left in this competition and if we produce that kind of performance again and come back from not being at our best it would be a great effort.

"We firmly believe we can do it. Once you've done it once, you can do it a second time and that's what we're aiming to do."

England are likely to name an unchanged team with Sajid Mahmood and Jimmy Anderson sharing the new ball while they are expected to resist the temptation to move Flintoff up the order for the early powerplays.

The choices are simple for England's cricketers today - beat South Africa and maintain hope that they can qualify for the semi-finals of the World Cup, or lose and face the music as we write off another four years of one-day cricket experimentation.

Not since 1992 have England reached the World Cup Final. Team after team, year after year, have failed to grasp what is needed to succeed in limited overs cricket.

Since the debacle in South Africa four years ago when England failed to reach the knockout stages, we have been told things were going to be put right but, with the exception of the Commonwealth Bank Series win in Australia last winter, England's cricketers have been consistent only in their ability to fail.

That a team which is ranked second behind Australia as a Test-playing nation has failed to transfer that quality to the shorter form of the game is mystifying.

That a team which possess two of the most destructive one-day players in world cricket should be struggling to reach the last four of the World Cup is surprising. That a nation which hosts more one-day cricket at club level than any other should constantly be found wanting is an embarrassment.

In Kevin Pietersen, England have the best one-day batsman at the tournament and in Andrew Flintoff they have the world's best all-rounder, but England have limped along like a wounded animal rather than a roaring beast.

Those two should be the heartbeat of a dominant side, but all we have secured so far in the Caribbean are unconvincing victories against minnows Bangladesh and Ireland.

The time for excuses is over. Lose to South Africa in Barbados this afternoon and the World Cup campaign is over - and four years of ambitious plans and different philosophies will have been a waste. England will have failed and coach Duncan Fletcher will have to fight to hold on to his job.